Existing data terminals can operate in any of several operating modes which are established by the user setting parameters, such as duplex/simplex, synchronous/asynchronous, parity, etc. The terminal operating mode must be set by the user to enable compatible communicatin with a computer system. In many communication systems, these data terminals are time-shared among several types of computer systems each having different operating parameters. In such a communication system, the user must check the terminal configuration and reconfigure the terminal if necessary to enable communication with a different computer system type.
To overcome this burdensome and technically complicated process of manual reconfigration by the user, one prior art system described by Finch et al in U.S. Pat. No. 3,676,858, issued on July 11, 1972, uses automatically reconfigurable computer ports. In Finch et al the coding and transmission rate of the computer port is set after an electrical connection is established with a remote terminal and after receiving and analyzing a single standard character sent at the transmission rate at which the terminal is configured.
One problem with the Finch et al arrangement is that since most of the operating modes available in todays terminals, such as parity setting, number of stop bits, character/block transfer, etc., are not detectable by analyzing the signal characteristics of the standard character received at the computer port, the Finch et al technique would not work. Consequently, the computer port must be manually reconfigured to enable compatible communications with many of the newer terminals. An additional limitation of the Finch et al arrangement is that the coding and transmission rate of the computer port cannot be set until after a connection is established and the terminal sends the standard character.
Thus, there is a continuing need in the art to provide a method and apparatus for automatic reconfiguration of a communication system to enable compatible communications between terminals and various types of computer equipment connected to the system.